Half-mode substrate integrated waveguide negative group delay compensating circuit

This work reports a half-mode substrate integrated waveguide (HMSIW) negative group delay (NGD) compensating circuit based on the equivalent left-handed material coupling mechanism. The proposed microwave NGD compensating circuit mainly consists of a HMSIW section, a split-ring resonator (SRR) and two coupling capacitors between them, as well as a pair of grounded metal sheets on the two sides of SRR for impedance matching enhancement. In specific certain frequency band, SRR is able to generate magnetic plasma effect and exhibit negative permeability. Simultaneously, negative permittivity can be produced by the negative capacitance, which is created by the J-inverter between the HMSIW section and the SRR. Thus, the proposed circuit will behave as an equivalent left-handed material to realize bandpass negative group delay function. Then, the analytical model allowing to determine the group delay is established from equivalent circuit approach. Later, to validate the proposed NGD function, a prototyped circuit is designed, simulated and fabricated. Bandpass NGD operation was realized, with a center frequency of 11.2 GHz, an effective bandwidth of 110 MHz, and a maximum NGD of -1.58 ns.